Yolk/Shell-Type CoxCu1-xCo2O4@CoyCu1-yCo2O4 Catalyst as well as Preparation Method and Application thereof to Catalytic Hydrogen Generation

Abstract

The present invention relates to the technical field of catalysts, and discloses a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst as well as a preparation method and application thereof to catalytic hydrogen generation. The preparation method of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst includes the steps of: successfully synthesizing, by applying a hydrothermal synthesis method, a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 solid sphere complex from a cobalt salt and hexamethyleneteramine serving as an alkali source; and then, performing calcination to obtain a yolk/shell-type Co.sub.3O.sub.4 microsphere structure, adsorbing Cu.sup.2+ on a surface in a physical adsorption manner, and performing calcination again to form yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4. The preparation method is simple, raw materials are cheap and available, and the prepared yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst is high in purity, good in catalysis performance and capable of showing excellent catalytic activity in term of ammonia borane catalytic hydrolysis for hydrogen generation.

Claims

1. A preparation method of a yolk/shell-type CoxCu1-xCo2O4@CoyCu1-yCo2O4 catalyst, characterized by comprising the following steps: step S1, dissolving 3-4.5 mmol of Co(NO3)2.6H2O, 1.5-2.25 mmol of C6H12N4 and 1-1.5 mmol of Na3C6H5O7.2H2O into 30-50 mL of water, and performing continuous stirring until dissolution to obtain a mixed solution; step S2, transferring the mixed solution to a reactor to be subjected a reaction at 80-160° C. for 8-24 h; step S3, performing suction filtration and water washing to obtain a [Co(C6H12N4)2](NO3)2 precipitate serving as an intermediate, and drying the precipitate at 40-60° C. in a vacuum oven; step S4, calcining the obtained sample at 200-400° C. for 1-4 h to obtain yolk/shell-type Co3O4; step S5, dissolving 0.05-0.1 g of Co3O4, 0.375-1.5 mmol of copper salt and 0.1875-0.75 mmol of C7H5NaO3 into deionized water, and performing continuous stirring until dissolution; step S6, performing reflux condensation on the solution, obtained in the step S5, at 80-120° C. for 6-12 h, collecting and washing a precipitate, and drying the precipitate at 40-60° C. in a vacuum oven to obtain a sample; and step S7, calcining the sample at 300-500° C. for 2-5 h to obtain yolk/shell-type CoxCu1-xCo2O4 @CoyCu1-yCo2O4.

2. The preparation method of claim 1, characterized in that the step S4 comprises: heating the obtained sample from room temperature to 200-400° C. at a heating rate of 2-10° C./min, and continuously calcining the sample for 1-4 h to obtain the yolk/shell-type Co3O4.

3. The preparation method of claim 1, characterized in that in the step S5, the copper salt is CuCl2.

4. The preparation method of claim 1, characterized in that the step S6 comprises: transferring the solution obtained in the step S5 to a single-neck flask, then putting the flask containing the solution into an oil bath pan, performing reflux condensation at 80-120° C. for 6-12 h, collecting the precipitate, washing the precipitate for 1-5 times, and then, drying the precipitate at 40-60° C. in the vacuum oven to obtain the sample.

5. The preparation method of claim 1, characterized in that the step S7 comprises: heating the sample from room temperature to 300-500° C. at a heating rate of 1-3° C./min, and continuously calcining the sample for 2-5 h to obtain the yolk/shell-type CoxCu1-xCo2O4 @CoyCu1-yCo2O4.

6. A [Co(C6H12N4)2](NO3)2 precipitate prepared in the step S3 of the preparation method of any one of claim 1.

7. A yolk/shell-type CoxCu1-xCo2O4@CoyCu1-yCo2O4 catalyst prepared by using the preparation method of any one of claim 1.

8. An application of the yolk/shell-type CoxCu1-xCo2O4@CoyCu1-yCo2O4 catalyst of claim 6 to ammonia borane catalytic hydrolysis for hydrogen generation.

9. A [Co(C6H12N4)2](NO3)2 precipitate prepared in the step S3 of the preparation method of claim 2.

10. A [Co(C6H12N4)2](NO3)2 precipitate prepared in the step S3 of the preparation method of claim 3.

11. A [Co(C6H12N4)2](NO3)2 precipitate prepared in the step S3 of the preparation method of claim 4.

12. A [Co(C6H12N4)2](NO3)2 precipitate prepared in the step S3 of the preparation method of claim 5.

13. A yolk/shell-type CoxCu1-xCo2O4@CoyCu1-yCo2O4 catalyst prepared by using the preparation method of claim 2.

14. A yolk/shell-type CoxCu1-xCo2O4@CoyCu1-yCo2O4 catalyst prepared by using the preparation method of claim 3.

15. A yolk/shell-type CoxCu1-xCo2O4@CoyCu1-yCo2O4 catalyst prepared by using the preparation method of claim 4.

16. A yolk/shell-type CoxCu1-xCo2O4@CoyCu1-yCo2O4 catalyst prepared by using the preparation method of claim 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a comprehensive test diagram of a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate in embodiment 1;

[0018] FIG. 2 is an SEM diagram of a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1;

[0019] FIG. 3 is a TEM diagram of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1;

[0020] FIG. 4 is an XRD diagram of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1;

[0021] FIG. 5 is an EDS-Mapping test diagram of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCO.sub.2O.sub.4 catalyst in embodiment 1;

[0022] FIG. 6 is a diagram showing a relationship that the contents of elements in the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1 change depending on the depth of a sample; and

[0023] FIG. 7 is a test curve showing catalytic hydrogen generation of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1.

DETAILED DESCRIPTION

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearly understood, the present invention will be further described below in detail in conjunction with specific implementation modes. It should be understood that the specific implementation modes described herein are only intended to explain the present invention, rather than to limit the protective scope of the present invention.

Embodiment 1

[0025] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 4.5 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 2.25 mmol of C.sub.6H.sub.12N.sub.4 and 1.5 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 35 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 100° C. for 24 h and is cooled to room temperature after the reaction is ended;
step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 40° C. in a vacuum oven; step S4, the obtained sample is heated from room temperature to 200° C. at a heating rate of 10° C./min in a muffle furnace and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.1 g of Co.sub.3O.sub.4, 1.5 mmol of CuCl.sub.2 and 0.75 mmol of C7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 90° C. for 12 h, and a precipitate is collected, is washed for 3 times, and is dried at 40° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 400° C. at a heating rate of 2° C./min in a muffle furnace, and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCO.sub.2O.sub.4.

Embodiment 2

[0026] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 3 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 1.5 mmol of C.sub.6H.sub.12N.sub.4 and 1 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 30 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 100° C. for 24 h and is cooled to room temperature after the reaction is ended; step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 40° C. in a vacuum oven;
step S4, the obtained sample is heated from room temperature to 200° C. at a heating rate of 10° C./min in a muffle furnace and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.1 g of Co.sub.3O.sub.4, 1.5 mmol of CuCl.sub.2 and 0.75 mmol of C.sub.7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 90° C. for 12 h, and a precipitate is collected, is washed for 3 times, and is dried at 40° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 400° C. at a heating rate of 2° C./min in a muffle furnace, and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCO.sub.2O.sub.4@ CO.sub.yCU.sub.1-yCO.sub.2O.sub.4.

Embodiment 3

[0027] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 4 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 2 mmol of C.sub.6H.sub.12N.sub.4 and 1.33 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 50 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 100° C. for 24 h and is cooled to room temperature after the reaction is ended;
step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 40° C. in a vacuum oven;
step S4, the obtained sample is heated from room temperature to 200° C. at a heating rate of 10° C./min in a muffle furnace and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.1 g of Co.sub.3O.sub.4, 1.5 mmol of CuCl.sub.2 and 0.75 mmol of C.sub.7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 90° C. for 12 h, and a precipitate is collected, is washed for 3 times, and is dried at 40° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 400° C. at a heating rate of 2° C./min in a muffle furnace, and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCO.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4.

Embodiment 4

[0028] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 4.5 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 2.25 mmol of C.sub.6H.sub.12N.sub.4 and 1.5 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 35 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 160° C. for 8 h and is cooled to room temperature after the reaction is ended;
step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 60° C. in a vacuum oven; step S4, the obtained sample is heated from room temperature to 300° C. at a heating rate of 5° C./min in a muffle furnace and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.1 g of Co.sub.3O.sub.4, 1.5 mmol of CuCl.sub.2 and 0.75 mmol of C.sub.7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 120° C. for 6 h, and a precipitate is collected, is washed for 3 times, and is dried at 40° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 500° C. at a heating rate of 1° C./min in a muffle furnace, and is continuously calcined for 2 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCO.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4.

Embodiment 5

[0029] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 4.5 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 2.25 mmol of C.sub.6H.sub.12N.sub.4 and 1.5 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 35 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 120° C. for 20 h and is cooled to room temperature after the reaction is ended;
step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 40° C. in a vacuum oven;
step S4, the obtained sample is heated from room temperature to 400° C. at a heating rate of 2° C./min in a muffle furnace and is continuously calcined for 1 h to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.1 g of Co.sub.3O.sub.4, 1.5 mmol of CuCl.sub.2 and 0.75 mmol of C.sub.7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 80° C. for 12 h, and a precipitate is collected, is washed for 3 times, and is dried at 60° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 300° C. at a heating rate of 3° C./min in a muffle furnace, and is continuously calcined for 5 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCO.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4.

Embodiment 6

[0030] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 4.5 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 2.25 mmol of C.sub.6H.sub.12N.sub.4 and 1.5 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 35 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 100° C. for 24 h and is cooled to room temperature after the reaction is ended;
step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 40° C. in a vacuum oven;
step S4, the obtained sample is heated from the room temperature to 200° C. at a heating rate of 10° C./min in a muffle furnace and is continuously calcined to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.1 g of Co.sub.3O.sub.4, 0.5 mmol of CuCl.sub.2 and 0.25 mmol of C.sub.7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 90° C. for 12 h, and a precipitate is collected, is washed for 3 times, and is dried at 40° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 400° C. at a heating rate of 2° C./min in a muffle furnace, and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4.

Embodiment 7

[0031] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 4.5 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 2.25 mmol of C.sub.6H.sub.12N.sub.4 and 1.5 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 35 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 100° C. for 24 h and is cooled to room temperature after the reaction is ended;
step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 40° C. in a vacuum oven;
step S4, the obtained sample is heated from room temperature to 200° C. at a heating rate of 10° C./min in a muffle furnace and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.05 g of Co.sub.3O.sub.4, 0.375 mmol of CuCl.sub.2 and 0.1875 mmol of C.sub.7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 90° C. for 12 h, and a precipitate is collected, is washed for 3 times, and is dried at 40° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 400° C. at a heating rate of 2° C./min in a muffle furnace, and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCO.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4.

Embodiment 8

[0032] Provided is a yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst which is prepared by the following process:

step S1, 4.5 mmol of Co(NO.sub.3).sub.2.6H.sub.2O, 2.25 mmol of C.sub.6H.sub.12N.sub.4 and 1.5 mmol of Na.sub.3C.sub.6H.sub.5O.sub.7.2H.sub.2O are dissolved into 35 mL of water, and are continuously stirred until dissolution to obtain a mixed solution;
step S2, the above-mentioned mixed solution is transferred to a 100 mL reactor to be subjected to a reaction at 100° C. for 24 h and is cooled to room temperature after the reaction is ended;
step S3, suction filtration and water washing are performed to obtain a [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as an intermediate, and the precipitate is dried at 40° C. in a vacuum oven;
step S4, the obtained sample is heated from the room temperature to 200° C. at a heating rate of 10° C./min in a muffle furnace and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.3O.sub.4, and the yolk/shell-type Co.sub.3O.sub.4 is cooled to room temperature;
step S5, 0.1 g of Co.sub.3O.sub.4, 0.75 mmol of CuCl.sub.2 and 0.375 mmol of C.sub.7H.sub.5NaO.sub.3 are dissolved into 20 mL of deionized water, and are continuously stirred until dissolution;
step S6, the solution obtained in the step S5 is transferred to a 100 mL single-neck flask, and the flask containing the solution is then put into an oil bath pan, reflux condensation is performed at 90° C. for 12 h, and a precipitate is collected, is washed for 3 times, and is dried at 40° C. in a vacuum oven to obtain a sample; and
step S7, the sample is heated from room temperature to 400° C. at a heating rate of 2° C./min in a muffle furnace, and is continuously calcined for 3 h to obtain yolk/shell-type Co.sub.xCu.sub.1-xCO.sub.2O.sub.4@ CO.sub.yCu.sub.1-yCO.sub.2O.sub.4.

[0033] The [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitates and the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalysts prepared in embodiments 1-8 are subjected to analysis and test including SEM test analysis, TEM test analysis, XRD test analysis and FTIR test analysis.

[0034] In FIG. 1, a, b, c and d are respectively XRD, FTIR, SEM and TEM test diagrams of the [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate in embodiment 1. It can be seen from a scanning diagram of the SEM test that the appearance of the prepared [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate is of a spherical structure. It can be seen from a projection electron micrograph of the TEM test that the prepared [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate is a solid sphere of which the diameter is about 2 μm. It can be seen from the XRD test that the prepared [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate has no peak in an XRD spectrogram, which shows that the obtained [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 is an amorphous solid. It can be seen from the FTIR test that a characteristic peak of NO.sub.3.sup.− appears at 1387 cm.sup.−1 in an infrared spectrogram, and C—N stretching vibration peaks appear at 1235 cm.sup.−1 and 1543 cm.sup.−1, which shows that the [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate serving as a target product is obtained. The specific infrared analysis of the [Co(C.sub.6H.sub.12N.sub.4).sub.2](NO.sub.3).sub.2 precipitate refers to table 1.

TABLE-US-00001 TABLE 1 Label Position (cm.sup.−1) Assignment species a 672 CNC C.sub.6H.sub.12N.sub.4 b 823 C-H C.sub.6H.sub.12N.sub.4 c 1235 C-N C.sub.6H.sub.12N.sub.4 d 1387 C-H, NO.sub.3.sup.− C.sub.6H.sub.12N.sub.4, Co(NO.sub.3).sub.2 e 1543 C-N C.sub.6H.sub.12N.sub.4 f 3395 O-H H.sub.2O

[0035] For the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4, it can be seen from the scanning diagram of the SEM test that the synthesized yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-y03204 is shaped like a microsphere of which the diameter is about 5 μm, and it can be seen from a damaged structure that the prepared sphere is a hollow sphere, as shown in FIG. 2 which is an SEM diagram of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1.

[0036] It can also be seen from a scanning diagram of the TEM test that the synthesized yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 is shaped like a microsphere of which the diameter is about 5 μm, as shown in FIG. 3 which is a TEM diagram of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1.

[0037] It can be seen from XRD test that the characteristic peaks of the synthesized yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 are in one-to-one correspondence to standard cards of Co.sub.3O.sub.4 and CuCo.sub.2O.sub.4, which shows that the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst serving as a target product is obtained, as shown in FIG. 4 which is an XRD diagram of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1.

[0038] Single sphere of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalysts prepared in embodiments 1-8 is subjected to an EDS test from which it can be known that three elements including Cu, Co and O are uniformly distributed in the sphere, which shows that the sphere is a complex of CuCo.sub.2O.sub.4 and Co.sub.3O.sub.4, and therefore, the complex can be simply expressed as Co.sub.xCu.sub.1-xCo.sub.2O.sub.4 in the present invention, as shown in FIG. 5 which is an EDS-Mapping test diagram of single sphere of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1. The yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalysts prepared in embodiments 1-8 are subjected to an XPS test from which it can be known that the content of Co is increased and the content of Cu is reduced with the increment of the depth of the sample, which shows that the compositions of a yolk and a shell are different, and therefore, the obtained product can be expressed by Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4, as shown in FIG. 6 which is a diagram showing a relationship that the contents of elements in the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1 change depending on the depth of the sample.

[0039] The catalytic hydrogen generation performances of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalysts prepared in embodiments 1-8 are subjected to test analysis, wherein the dosage of NH.sub.3BH.sub.3 is 3 mmol, the dosage of NaOH is 20 mmol, and the dosage of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst is 10 mg. It is tested that by using Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 as a catalyst, 60-80 mL of hydrogen is generated every minute at 25° C., as shown in FIG. 7 which is a test curve showing catalytic hydrogen generation of the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1. It can be known from FIG. 7 that by using the yolk/shell-type Co.sub.xCu.sub.1-xCo.sub.2O.sub.4@Co.sub.yCu.sub.1-yCo.sub.2O.sub.4 catalyst in embodiment 1, about 75 mL of hydrogen is generated every minute.

[0040] All technical features of all of the above-mentioned embodiments can be combined arbitrarily. In order to make the descriptions concise, not all possible combinations of all the technical features in the above-mentioned embodiments are described. However, the combinations of these technical features should be regarded as the scope recorded by the description as long as they do not conflict.

[0041] The above-mentioned embodiments only express several implementation modes of the present invention and are described relatively specifically in detail, but cannot be hence understood as limitations on the patent scope of the present invention. It should be noted that several variations and improvements can also be made by the those of ordinary skill in the art without departing from the concept of the present invention, these variations and improvements fall within the protective scope of the present invention, and therefore, the patent protective scope of the present invention shall be subject to the appended claims.